The ending seems to fall really flat? The most dramatic part of the game is probably the line when Caroline says the line about nested boxes, because it feels like she had just been setting the main characters up the whole time (and you seem to understand this, since you quoted it on the itch.io page)
But you don't do anything with it? Nothing happens to Joan? And the bad ending just feels like it's played for comedy, or like, bathos...? It's a huge anticlimax how the MC walks out with a funny looking portrait and Joan just has a single line of dialogue making a telephone call? There's no punch to it. I was expecting a lot more.